Question: If $a + b = -1$ and $x + y + z = 2$, what is $7a + 7b + 6z + 6x + 6y$ ?
Explanation: $= 7a + 7b + 6x + 6y + 6z$ $= (7) \cdot (a + b) + (6) \cdot (x + y + z)$ $= (7) \cdot (-1) + (6) \cdot (2)$ $= -7 + 12$ $= 5$